This invention relates to a centrifuge rotor and, in particular, to a centrifuge rotor having an arrangement whereby the pressure to which a sample to be centrifuged is exposed may be varied.
It has been observed that when using a vertical tube rotor for self-generating gradient separations, such as that disclosed in U.S. Pat. No. 3,998,383 (Romanauskas et al.), banding of particles occurs at densities which differ from the densities at which the same particles band when the self-generating gradient separation is performed on a swinging bucket or fixed angle rotor. This discrepancy is believed to be caused by differences in the hydrostatic pressure or compressability force exerted on particles when centrifuged in a vertical tube rotor as opposed to other rotors.
Accordingly, it is believed to be advantageous to provide a mechanism whereby the compressability force exerted on the particles being separated when using a vertical tube rotor be made to be substantially equal to the hydrostatic compressability force exerted on particles when separated in another type centrifuge rotor so that banding of particles occurs at corresponding densities. More broadly speaking, it is believed to be advantageous to provide a centrifuge rotor of the fixed angle type wherein a mechanism is provided for adjusting the hydrostatic pressure to which particles in suspension are exposed so that the pressure effects on samples may be determined. As a corollary to the foregoing, it is believed to be of further advantage to provide a rotor of the fixed angle type wherein pressure effects on the particles over a range of ambient pressures may be observed using only a single run.